Stuffing or meat encasing machines of the type shown in U.S. Pat. Nos. 3,115,668 and 3,191,222 are commonly used in the manufacture of frankfurters and the like. In use, a hollow tubular shined casing stick with a closed leading edge is situated on a hollow, tubular stuffing horn and is deshirred and stuffed with a food emulsion discharged from the horn. The discharge end of the stuffing horn having the casing stick is placed about midway inside a plastic, molded, rotatable chuck having a cylindrical bore. The casing is pulled between the outer wall of the stuffing horn and the inner wall of the chuck's bore, beginning at the casing engaging zone, going through the annular passage, and as the food emulsion is discharged through the horn, the casing is deshirred and fills with the food emulsion at the discharge end of the horn, inside the chuck. As the casing fills with food emulsion, it passes longitudinally through the remaining distance of cylindrical bore in the chuck. At this point, the chuck's diameter is smaller than the diameter of the casing. This area is known as the casing deforming zone. The chuck is rotatably driven so it transfers a torque to the casing for twisting the stuffed casing into links. Twisting into links is accomplished in association with the pinchers of a conventional linking apparatus located downstream from the stuffing horn and chuck.
The chuck also is designed to impose a longitudinal drag or “holdback” on the casing moving longitudinally through its bore. Without this holdback the food emulsion will not tightly stuff into the casing. The holdback on the casing is provided by longitudinal flutes spaced circumferentially around the length of the bore of the conventional chuck member. These flutes, as shown in U.S. Pat. Nos. 3,115,668, U.S. Pat. No. 3,191,222, U.S. Pat. No. 4,812,322, and RE 37,883 extend the full length of the chuck bore and provide the holdback force on casing within the bore.
The inlet end of the chuck bore is inwardly tapered from a first relatively larger diameter to a second relatively smaller diameter at a location intermediate the inlet end and the discharge end of the bore. This tapered inlet, or casing engaging zone, is the zone that first grasps the shirred casing stick situated on the stuffing horn, and the flutes in this section or zone grip and rotate the stick while the casing is deshirred during the stuffing process. The stuffed casing then passes through the smaller diameter downstream of the intermediate location where it is deformed and gripped by the flutes pressing inwardly against the stuffed casing. The flutes, by gripping the stuffed casing, allow the chuck to transmit torque to the stuffed casing thereby rotating the stuffed casing for twisting it into links.
The flutes must be properly sized to provide sufficient holdback for stuffing, yet must not apply so much holdback that the casing will be filled with an excessive amount of meat emulsion and burst. As previously indicated, the flutes also must grip the casing to provide the needed torque transmission for twisting and linking the filled casing.
It has always been a compromise to design a chuck with flutes which provide sufficient gripping for adequate torque transmission without gripping so tightly that there is excessive holdback, as this could result in overstuffing and possible breakage of the casing. The conventional practice has been to design a chuck which provides only adequate holdback rather than risk overstuffing. However, it has been discovered that the typical chuck design which works well for cellulosic casings does not provide the same holdback force for plastic casings. This results in under stuffing of the plastic casing unless other adjustments are made. Machine adjustments can be made to increase the firmness of the stuffed food product, but there appears to be no reliable adjustment to prevent the initial links of a new shirred stick from being severely understuffed. This is not necessarily a problem for all stuffing processes, but is a significant problem for machines equipped with automatic loopers because the initial links have inadequate firmness to transfer through typical looper assemblies and frequently jam the equipment in the process, thereby stopping the high-speed production of the food product.
One attempted solution to the jamming problem is to increase the deshirr force of plastic shirred sticks. This would increase the holdback force during stuffing so the dynamics will more closely approximate stuffing of cellulosic casings. However, this approach has been attempted with limited success to date.
One object of this invention is to provide a food stuffing machine chuck member which provides more holdback force on plastic casings than commercially available chucks.
Another object of this invention is to provide a method of deshirring a shirred plastic casing and stuffing it by introducing a means to increase holdback force on the plastic casing.
These and other objects will be apparent to those skilled in the art from the following description.